test: cover retrieval metadata coercion

tests/unit/test_retrieval_coerce_metadata.py

@@ -0,0 +1,59 @@
+# SPDX-License-Identifier: Apache-2.0
+"""Unit tests for :func:`stargraph.nodes.retrieval._coerce_metadata`."""
+
+from __future__ import annotations
+
+from typing import Any
+
+import pytest
+
+from stargraph.nodes.retrieval import _coerce_metadata  # pyright: ignore[reportPrivateUsage]
+
+
+@pytest.mark.unit
+def test_coerce_metadata_preserves_scalar_entries() -> None:
+    meta: dict[str, Any] = {
+        "title": "ops note",
+        "rank": 3,
+        "score": 0.75,
+        "active": True,
+        "stale": False,
+    }
+
+    assert _coerce_metadata(meta) == meta
+
+
+@pytest.mark.unit
+def test_coerce_metadata_drops_non_scalar_entries() -> None:
+    meta: dict[str, Any] = {
+        "nested": {"owner": "alice"},
+        "tags": ["runbook", "ops"],
+        "missing": None,
+    }
+
+    assert _coerce_metadata(meta) == {}
+
+
+@pytest.mark.unit
+def test_coerce_metadata_returns_empty_dict_for_empty_input() -> None:
+    assert _coerce_metadata({}) == {}
+
+
+@pytest.mark.unit
+def test_coerce_metadata_keeps_only_scalar_subset() -> None:
+    meta: dict[str, Any] = {
+        "id": "doc-1",
+        "priority": 5,
+        "confidence": 0.95,
+        "verified": True,
+        "payload": {"ignore": "nested"},
+        "chunks": ["a", "b"],
+        "notes": None,
+    }
+
+    assert _coerce_metadata(meta) == {
+        "id": "doc-1",
+        "priority": 5,
+        "confidence": 0.95,
+        "verified": True,
+    }